A little science 101 to start. There are for states of matter, solid, liquid, gas and today’s fav, plasma. Plasma is a super heated gas. It can be any type of gas, nitrogen, oxygen or normal air. Plasma cutters work by super heating air using an electrical current.
When you pull the trigger on a plasma cutter it creates an electrical current between your electrode and the tip inside the plasma cutter head. The swirl ring in the top of the body turns the air coming down the tip into a vortex, kind of like a tornado.
As the air gets super heated it turns into plasma and is pushed out the end of the cutting tip. The cutting tip has a small hole in the end to concentrate the plasma in one spot, other wise it would blast around everywhere and not give you a clean cut. The air that rushes down the outside of the tip also helps to make a clean cut by helping to push away the molten metal that the plasma cutter creates.
Plasma cutters give a superior cut over oxygen/fuel cutting. The high concentration of heat in one spot allows a quicker, cleaner cut. With the aid of compressed air helping to make a faster cut and also cool the cut as soon as it is completed. The faster the cut is cooled down the less chance there is for distortion in your work, especially on thinner materials.
Plasma cutters have the advantage over oxygen fuel cutting in that they can cut anything that will conduct an electrical current. Copper, aluminium as well as mild steel. Plasma cutters are fantastic at cutting aluminium because of the low distortion due the concentrated heat in one area.
Do you really need one? You have survived until now without one, they are a nice machine to own and you will probably find you will use it more than you think.
Will it replace your oxy set? Yes and no. Oxy/fuel still has its place in the heating area, your plasma cutter wont do that. But in terms of cutting, the plasma will definitely get used more. The price of an oxy/fuel setup isn’t cheap and if you are still paying bottle rental the cost definitely adds up.
In terms of cutting, its plasma for the win!